RE: dbms_HASH...or something like it?...comparing data...

Jonathan,

Thanks, perfect.
Now that *you* say it sounds familiar,
but I find I have not personal notes=20
on dbms_utility.get_hash_value.

>>two items that hash to the same value do
>>not necessarily hold the same original value.

Good info...this may be a show stopper.

Chris Marquez
Oracle DBA
HEYMONitor=99 - heymonitor.com
"Oracle Monitoring & Alerting Solution"

-----Original Message-----

From:	oracle-l-bounce_at_freelists.org on behalf of Jonathan Lewis
Sent:	Sat 1/22/2005 6:13 PM
To:	oracle-l_at_freelists.org
Cc:=09
Subject:	Re: dbms_HASH...or something like it?...comparing data...

You could have a look at procedure

    dbms_utility.get_hash_value()
described in dbmsutil.sql

This turns an input string into a number.

Make sure your developer is aware that
two items that hash to the same value do not necessarily hold the same original value.

Regards

Jonathan Lewis

http://www.jlcomp.demon.co.uk/faq/ind_faq.html The Co-operative Oracle Users' FAQ

http://www.jlcomp.demon.co.uk/seminar.html Public Appearances - schedule updated Dec 23rd 2004

• Original Message -----=20 From: "Marquez, Chris" <CMarquez_at_aarp.org> To: <oracle-l_at_freelists.org> Sent: Saturday, January 22, 2005 11:03 PM Subject: dbms_HASH...or something like it?...comparing data...

Need some help.

Developer has a wide table...20 columns. He would like to add a 21st column to the table. Then he would like to (be able to) store the first=3D20 20 columns data in concatenated form in the 21st column. For example;
col1, col2, col3
Joe,Smith,JoeSmith

No problem PL/SQL program can handle this, BUT he would rather store the 20 concatenated columns in=3D20 a simpler, tighter form. He suggested "hashing" the=3D20 20 concatenated columns to (I guess) an Alphanumeric string?

And given that this is possible, what would be the=3D20 best/required data type for the hashed data?

Why you ask?
Because he want to be able to compare rows=3D20 (against new data) simply and quickly without selecting and=3D20 concatenating all 20 originally columns.

So he would store the hashed version of a row (data) on Insert. Then on Update using a function hash the update data and compare it to the already hashed value in the row. =3D20
Any help is appreciated?
Any other solution is appreciated, BUT his program is limited and=3D20 can only S,I,U,D and call PROCEDURES or FUNCTIONS.

Please reply directly to me as well as to the list.

Thanks in advance,

Chris Marquez
Oracle DBA
HEYMONitor(tm) - heymonitor.com
"Oracle Monitoring & Alerting Solution"

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